Re: [PATCH v3 27/33] drm/xe: Add IOVA-based xe_res_cursor variant

[Matthew Auld <matthew.auld@intel.com>]

On 11/07/2026 03:56, Matthew Brost wrote:
> Introduce xe_res_first_iova() to walk a buffer that was DMA mapped using
> the IOVA-based DMA API (dma_iova_try_alloc() and friends). Such a mapping
> is described by a struct dma_iova_state and is a single contiguous IOVA
> range, so the cursor walks it as one segment.
> 
> Add an is_iova flag to struct xe_res_cursor to distinguish this case.
> When set, xe_res_dma() returns the IOVA backing the current position
> (state->addr + cursor offset), xe_res_next() advances within the single
> contiguous segment, and xe_res_is_vram() returns false since IOVA
> mappings never point to same-device VRAM.
> 
> The flag is explicitly cleared in the existing xe_res_first(),
> xe_res_first_sg() and xe_res_first_dma() initializers so stale stack
> values cannot leak into the new path.
> 
> Cc: Carlos Santa <carlos.santa@intel.com>
> Cc: Ryan Neph <ryanneph@google.com>
> Cc: Christian Koenig <christian.koenig@amd.com>
> Cc: Huang Rui <ray.huang@amd.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Simona Vetter <simona@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Assisted-by: GitHub_Copilot:claude-opus-4.8
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Auld <matthew.auld@intel.com>